Mylex SCSI Controller, 16550A UARTS

[John Spencer]

In article <16173 at vail.ICO.ISC.COM> dougp at ico.ISC.COM (Doug Pintar) writes:

>The real problem with disk transfer on AT-bus (and MCA as well, for that
>crowd) is NOT bus bandwidth but lousy controller design.  PIO controllers
>are cycle hogs, and most DMA controllers DON'T SUPPORT SCATTER/GATHER!  This
>makes transfers to/from physically-discontiguous memory pages very inefficient.
Could someone tell me where I can get more information on understanding PIO
controllers -vs- DMA controllers supporting and not supporting scatter/gather.
Any information would be extremely helpful.